CP Chemistry Lab: Metal, Nonmetal, or Metalloid?

Objective: Explore the physical and chemical properties of eight elements with the goal of classifying them as metals, nonmetals, or metalloids.

Background:

Physical Properties: – properties that can be observed without changing the identity of a substance

Chemical Properties: – properties that are observed while altering the identity of the substance involved

Metals: – elements that are usually silver-gray in color, with the exception of copper and gold – solid at room temperature except mercury, which is a liquid – lustrous or shiny appearance and reflect light when polished – can be bent or hammered flat (malleable – can be drawn into wire – good conductors of heat and electricity – usually show reaction with acids – usually high melting point

Nonmetals: - found to the right of the zigzag line on the periodic table - usually dull in appearance and do not reflect light - many brittle and cannot be hammered into sheets - poor conductors of electricity and heat - show little or no reaction with acids - low melting points - exist as either solids or gas, bromine is an exception, it is a liquid

Metalloids: - found on both sides of the zigzag line on the periodic table except for aluminum - show properties of both metals and nonmetals - are not good conductors of electricity - when mixed with small amounts of other elements the conductivity of metalloids increases

Note: There are many exceptions to the rules for classifying elements.

Safety Precautions: Perform this lab activity in a well-ventilated laboratory. Hydrochloric acid solution is corrosive to eyes and skin. Cupric chloride solution is toxic if ingested. Avoid contact of all chemicals with eyes and all body tissues. Wear chemical splash goggles, and a chemical-resistant apron.

Materials Aluminum shot, 2 pieces Hydrochloric acid, 1 M HCl Carbon Copper (II) chloride, 0.1 M CuCl2 Iron wire, 1 cm, 2 pieces Distilled water Magnesium ribbon, 1 cm, 2 pieces Mortar and pestle Silicon Well plate Sulfur powder Conductivity tester Antimony Zinc shot, 2 pieces

Data See handout for table.

Procedure: Pre-Laboratory Preparation 1. Using a periodic table, determine the chemical symbol from each of the eight elements to be tested in this laboratory. Fill in the chemical symbol for each element on the data table. 2. Obtain the eight weighing dishes with the corresponding element in each dish. 3. NOTE: Do not touch any of the elements with your hands. Use a spatula or forceps at all times!

Part 1—Physical Properties 1. Observe and record the color of each element on the Data Table. Is the sample silver, gray, colored, etc . . . .? Be very specific in recording observations. 2. Observe and record the luster of each element on the Data Table. Is the sample lustrous and shiny, slightly shiny, dull? 3. Record any other physical properties that are observed about the element on the Data Table. Be specific in your observations. What form is the sample in? Is the sample crystalline, flaky, rough, smooth, flat and plate- like, rocky, in strips? Is there any odor or are any vapors given off? (Note: Avoid breathing any vapors directly. Instead of smelling a sample directly, waft the vapors form the sample toward our nose.) 4. Determine whether each element is malleable or brittle. To do this, position a nail on the sample and gently tap the nail with a hard, solid object (such as a small piece of wood). A material is malleable if it flattens or bens without shattering. A sample is brittle if it shatters or cracks into pieces when struck. Record your results on the Data Table. 5. Test the conductivity of the eight samples. Touch both electrodes to the element being tested, being sure that the electrodes are not touching each other. Red LED off Green LED off Low or None, Red LED dim Green LED off Low, Red LED medium Green LED off medium, Red LED bright Green LED dim high, Red LED very bright Green LED medium very high

Part 2—Chemical Properties (Some reactions may be slow to start – be patient) 1. Put a small amount of each element into well on a well plate. Determine the reactivity with acid of each sample by adding 5 drops of 1.0 M hydrochloric acid to each tube. Observe each tube for approximately 3-5 minutes and record results in the Data Table. 2. Disposal: Decant the liquid into the sink and dispose of the solids in the garbage. Rinse out the well plates with water for the next step. 3. Put a small amount of each element into the well plate. Determine the reactivity with copper II chloride solution of each sample by adding one pipetful (about 2-3 mL) of 0.1 M copper II chloride to each tube. Observe each tube for approximately 3-5 minutes and record results in the Data Table 4. Disposal: Decant the liquid into the sink and dispose of the solids in the garbage. Rinse out the well plate with water.

Post-Lab Questions:

1. Review the data gathered for the eight elements. Sort the eight elements into groups based on similarities and differences in their physical and chemical properties. From the information provided in the background reading, classify each element as metals, nonmetals, or metalloids.

2. Are there any inconsistencies within the groups you made? Do any elements seem to have properties of both groups? Which? Explain.

3. Look at the location on the periodic table of each of the eight elements tested n this lab. How do the properties of these elements compare to their general position on the periodic table? Make generalizations about the position of the metals, nonmetals, and metalloids on the periodic table.

4. Predict the physical and chemical properties of the following elements which were not tested in this lab. Explain your reasoning for each element. selenium calcium cobalt